Had an idea for my ACIS, wanted to clear one thing up

[phoenix6]

Ive read with the ACIS off (as mine had the wires cut whenI first owned it) at about 3500rpms the torque curve spikes like crazy and u feel a jump. Which it did, and I liked it. With ACIS ON likemine is now, at 4000rpms it kicks in but only holds the torque curve steady.

I could be wrong but lets say in a race, which one would be better? Wouldnt a spiked torque give u an advantage? Even just a little? If so WHY do they have ACIS? for safer driving or what?

and my idea is not just removing ACIS.

 

[staticpat]

What in the world is the ACIS? I still don't understand. I've never seen any kind of valve switching or anything. Someone tried to explain it in another thread, but I need a picture or something. All I can imagine is some sort of ducting like on the 3000gt VR-4s.

EDIT: Apparently someone posted up a description in the 7mge boards a couple days ago. Apparently I have lots to read. So I guess this applies to 1/2NA->T guys.

http://www.supramania.com/forums/showthread.php?t=41390&highlight=acis for those of you who dont browse the NA boards.

 

[BorHor]

it is under the intake manifold where it curves. It just opens up the intake more.

 

[phoenix6]

What in the world is the ACIS? I still don't understand. I've never seen any kind of valve switching or anything. Someone tried to explain it in another thread, but I need a picture or something. All I can imagine is some sort of ducting like on the 3000gt VR-4s.

I dont have any pics right now but on our 7mGEs on the ypipe there is a vacuum line running into where the Y meets. Its attached to a vacuum booster underneath the intake manifolds. THere is a butterfly valve inside the intake piping after the intake hole for the ACIS. at 4000RPMs the valves create a different accoustics (or something like that) and the butterfly valve opens and the vac booster shoots more air into the intake to control the torque curve, otherwise it spikes outta control...kinda lol

 

[bowsercake]

So, the 3UZ (SC430, GS430) engines still use ACIS today. I wonder if the implementation is any different. It would seem to me, as with most things, that it is best to leave it how it came from the factory.
http://www.lexus.com/models/SC/features/performance/288hp_v8_engine.html

 

[phoenix6]

So, the 3UZ (SC430, GS430) engines still use ACIS today. I wonder if the implementation is any different. It would seem to me, as with most things, that it is best to leave it how it came from the factory.
http://www.lexus.com/models/SC/features/performance/288hp_v8_engine.html

Well at least my idea will make it easy to have it on or off on the fly. For testing maybe? :evil2:

 

[jmanbball]

If I was you, I'd dyno it both ways and compare the curves.

 

[phoenix6]

If I was you, I'd dyno it both ways and compare the curves.

only problem is Im kinda broke for a dyno right now, and I dont even know where one here in town is lol.... Ill just try 2 runs with and without, if I like without still, Ill go make that modification...should be fun anyways.

 

[Nick M]

Ive read with the ACIS off (as mine had the wires cut whenI first owned it) at about 3500rpms the torque curve spikes like crazy and u feel a jump. Which it did, and I liked it. With ACIS ON likemine is now, at 4000rpms it kicks in but only holds the torque curve steady.

I could be wrong but lets say in a race, which one would be better? Wouldnt a spiked torque give u an advantage? Even just a little? If so WHY do they have ACIS? for safer driving or what?

and my idea is not just removing ACIS.

You aren't getting it yet. The spike at 3500 happens because of a deficency below that point. That is why you feel it. The intake air control valve gets rid of the deficency, so you have the torque all the way through the rpm band. Keep in mind that the tuning was designed for the 7MGE not GTE.

 

[phoenix6]

yeah mine is GE, but the car did seem to pull harder at the spike.... its just waht I remember Im not saying your wrong. I might as well just unplug it and see anyways b4 I try what I have in mind.

 

[Nick M]

I know it pulled harder. Because it was weak underneath that point. It is like running with 2 plug wires disconnected, then plugging them in at 3500 rpm. You would feel a jump with all 6 on. Then you go and tell people to disconnect the 2 wires and drive like that, and plug them in at 3500, and you will get a big spike.

 

[IJ.]

Nick: Interesting info thanks!
(I always thought it was the other way around when it was working you got the spike @ 4K but it makes more sense that Toyota did it to remove the spike)

 

[Nick M]

The plenum is too big for a 3 litre to fill at low velocity.

Now this part I know you understand. The intake valves opening and closing makes air pulses. The valve is closed so they bounce off, and are sent back to in the intake valves, creating a little bit of pressure. So the valve increases low rpm torque, it doesn't add to high rpm torque.

 

[IJ.]

The "acoustic" part eh

 

[phoenix6]

Oh ok nvm I was confused, now I understand it better... thanks Nick.... damn I had a good idea too lol


basically my TEMS doesnt work, and u know how it says NORMAL and SPORT on the buttons, I was gonna rig those to turn ACIS ON (normal) and off (Sport) lol DAMMIT.

 

[Nick M]

I think this crude drawing can illustrate it for anybody isn't following. This is what the torque curve would look like with the stock plenum. In blue, is the torque curve with the intake air control valve operating correctly, and giving you that ACIS function.

This is different than variable cam timing with variable lift. That extra lobes high lift and duration will shift the torque curve up, and make the engine run like a raped ape above 5500-6000 RPM.

 

[NashMan]

in turbo charged case i whould get rid of it

and the 89+ cressda does not have it and has less power as well